Willingness to vaccinate in a future pandemic. Evidence from a vignette experiment

The COVID-19 pandemic highlighted both the importance of vaccination and the persistent challenge of vaccine hesitancy. As future global outbreaks remain a realistic threat, understanding the factors shaping vaccination intentions beyond the COVID-19 context is crucial. We conducted a pre-registered vignette experiment in an online survey in Hungary (N=1000), varying six disease and vaccine-related attributes: disease severity, vaccine's country of origin, technology, regulatory approval, side effects, and recommendation source. Respondents evaluated eight randomly assigned scenarios each. Multilevel linear models were used to estimate the main and interaction effects of vignette and individual characteristics. Vaccine side effects, approval status, and country of origin were the strongest predictors of willingness to vaccinate in a future pandemic. Respondents were substantially less willing to accept vaccines with stronger side effects or those originating from China, and preferred vaccines jointly approved by Hungarian and European authorities. In contrast, vaccine technology (mRNA vs. non-mRNA) and recommendation source had no significant effect. Less-educated, rural respondents and those unvaccinated against COVID-19 were largely unaffected by differences in vaccine attributes or contextual factors. Concerns over side effects and institutional legitimacy remain central in hypothetical future pandemics, while technological distinctions play a minor role. Strengthening trust through transparent, evidence-based communication, early engagement, and tailored messages addressing the specific concerns of hesitant subgroups not even influenced by disease and vaccine-related factors will be essential to improve vaccine uptake and pandemic preparedness.